Halliday, Resnick & Walker — Electric Potential: Problem 21

21 In the rectangle of Fig. 24-30, the sides have lengths 5.0 cm and 15 cm, \(q_1 = -5.0 \mu\text{C}\), and \(q_2 = +2.0 \mu\text{C}\). With \(V = 0\) at infinity, what is the electric potential at (a) corner A and (b) corner B? (c) How much work is required to move a charge \(q_3 = 3.0 \mu\text{C}\) from B to A along a diagonal of the rectangle? (d) Does this work increase or decrease the electric potential energy of the three-charge system? Is more, less, or the same work required if \(q_3\) is moved along a path that is (e) inside the rectangle but not on a diagonal and (f) outside the rectangle?